Lewes BPW explains 2019 sewer plant failure

More than a year after a failure at the wastewater treatment plant that resulted in nearly 4 million gallons of partially treated effluent being dumped into the marsh, the Lewes Board of Public Works has completed its analysis on the root cause and necessary corrective actions.

BPW Director Tom Panetta recently offered a thorough explanation of the steps taken since the incident to ensure nothing like that happens again.

In the analysis, BPW determined former operator White Marsh Environmental Services did not follow strict enough protocols to ensure the plant was operating at an acceptable level. In November, BPW cut ties with White Marsh and contracted with Inframark, formerly known as Severn Trent, the same company that operated the plant from 2007 through 2017.

“We had a good relationship with [White Marsh], but they were not as sophisticated and did not have the management systems that we felt were necessary to operate the plant reliably,” Panetta said.

During the investigation, BPW discovered the plant’s state-of-the-art filters were not being cleaned or maintained on a regular basis. They also found meters used to detect water cleanliness were improperly adjusted. As part of corrective actions, BPW has pledged to provide more stringent oversight of the plant operator.

Inframark and White Marsh worked together over a two-week period last fall to ensure a smooth transition. 

“I’ve been very impressed with [Inframark],” Panetta said. “They are extremely responsive. They had their regional manager down here on site almost continuously until things stabilized.”

Inframark provides detailed written reports at the BPW’s monthly meetings. They also have a representative at meetings to answer any questions from the board.

“They’re providing us with much more interpretation of the data,” Panetta said. “The reports are much, much more informative than just culling through a bunch of numbers.”

The board is also using Suez, the manufacturer of the plant’s zenon filters, for additional oversight. Suez representatives closely monitor data and provide a report every two weeks on the filters’ performance. They also provided training to Inframark employees to ensure proper maintenance of the filters.

“Prior to this, we did not have Suez actively involved other than their yearly walkthrough,” Panetta said. “Now, they are a key part of the data analysis.”

The filters are possibly the most important feature of the wastewater treatment plant. Several cassettes of filters contain noodle-like membranes. Each noodle contains microscopic holes smaller than a human hair that are used to filter out bacteria and other bad material at the end of the treatment process.

Although the previous filters were old, General Manager Darrin Gordon said he’s confident they could have lasted a few more years if they had been properly maintained.

BPW is also conducting periodic walkthroughs of the plant with its engineers from George, Miles and Buhr. Although they are scheduled every three months, walkthroughs also occur unannounced, Panetta said.

“Inframark has been very forthright, and we see that when we go over there,” he said.

As part of the failure analysis, Panetta searched for single points of failure at the plant, meaning areas where there are not redundancies, which could cause issues to worsen if a problem occurs.

BPW has also identified future upgrades. For example, in the next five to 10 years, the BPW should replace its equalizing tank. Gordon added the tank to the long-term capital budget. Other items have been documented and put on a tracking list.

One area that was lacking, Panetta said, was emergency operating procedures. Inframark has responded with a much more detailed procedure.

“They looked at how they would handle a failure like what happened in December 2019,” he said. “They actually have a procedure for the loss of the membranes. In general, their procedures are much more in-depth.”

Panetta said he is more confident than ever that the plant is operating at its peak potential.

“From a material condition perspective, the plant is in much, much better shape than I’ve ever seen,” Panetta said. “There are still things we’re working on, but in general from a safety and operational perspective, it’s much better.”

The BPW welcomes public tours of the wastewater treatment plant. To schedule a tour, contact General Manager Darrin Gordon at 302-645-6228.

Corrective actions taken

• Filter membranes replaced as of May 2020
• Turbidity meters reset to manufacturer’s recommended setting
• Replaced turbidity monitors with new models
• Perform quarterly walkthroughs with consulting engineers to evaluate field condition, maintenance records, compliance records, and plant operation and maintenance
• Updated plant’s operation and maintenance manual
• Contracted Suez to remotely collect data to monitor and trend, in order to provide biweekly reports and an annual summary report
• Engineering analysis of entire plant to identify ways to improve redundancies
• Established improvement program for monitoring plant performance
• Improved operator’s reporting requirements
• Stronger BPW oversight of operator’s performance
• Improved BPW board of directors’ oversight of BPW staff
• Development of off-normal operating procedures
• Other areas, such as electrical system, evaluated for possible failure points
• Suez training for plant operator staff on operation and maintenance of filters and plant
• Review of safety manual
• BPW audit of operator’s safety procedures and practices.